Process and device for aligning and co-processing flaccid workpiece layers

ABSTRACT

Process and device for aligning and jointly processing flaccid workpiece layers (4, 104). The workpiece layers (4, 104) to be processed jointly are brought toward one another in the hanging position by endless conveyors (1, 101). A scanning and aligning station (10) is located in the delivery path of the two endless conveyors (1, 101). The workpiece layer is temporarily removed from the respective conveyor in at least one of the endless conveyors and aligned in relation to the other workpiece layer. The workpiece layer is then returned in the aligned position to the conveyor. After which the workpiece layers that are associated with one another will leave the scanning and aligning station (10) together. The present invention permits simplified fastening of clamps (16, 17; 116, 117) for the workpiece layers to the endless conveyors. They are fixed there by permanent magnets (14; 114), whose magnetic field in the scanning and aligning station (10) is temporarily abolished in order for the alignment process to be able to be carried out with low friction.

FIELD OF THE INVENTION

The present invention pertains in general to a process and device fortransporting flaccid workpieces to a scanning and aligning station wherethe workpieces are scanned and then aligned with each other and thentransported away from the scanning and aligning station. Morespecifically the present invention describes a process and device whereat least one of the workpieces is removed from a conveying means alignedwith the other workpiece and then reattached to the conveying means andboth the workpieces are transported away in alignment.

BACKGROUND OF THE INVENTION

Similar processes and devices are known from European Paten DisclosureDocument #EP-OS 0,260,331. In the prior-art process, the workpiecelayers are fed to each other by conveying means. The conveying meanscomprise rail-guided carriages on which clamps are arranged holding theupper end of the workpiece layers. These conveying means have tracksections directed in parallel to one another in a scanning station andan aligning station. To make possible the mutual alignment of theworkpiece layers, the clamps are arranged on the carriages of one of theconveying means by means of a holding head which is movable in aplurality of directions in relation to the carriage carrying it. Thisholding head carries a magnetizable plate which comes into frictionallyengaged contact in the aligning station with a permanent magnet that isfastened to the adjacent carriage of the other conveying means. Using anadjusting device of the stationary aligning station, the movable holdinghead of the clamps on the first-named carriage is adjusted,corresponding to the scanning result, such that the two workpiece layersthat are adjacent to one another in the aligning station will reach thepredetermined relative position. Based on the frictional engagementbetween the magnetizable plate on the holding head of one carriage andthe permanent magnet on the other carriage, this relative position ismaintained when the two carriages move together from the aligningstation into the subsequent processing station after alignment of theworkpiece layers.

This design is relatively complicated, because it requires an adjustableholding head that is adjustable in a plurality of directions at each ofthe carriages of one conveying means. In addition, to adjusting theholding heads, the adjusting device must exert a considerable force toreach the specified relative position of the two workpiece layers inorder to overcome the frictional force between the magnetizable plateand the permanent magnet, which must, as is explained, be strong enoughto maintain the relative position, once set, between the permanentmagnet and the plate and consequently the aligned position of theworkpiece layers.

SUMMARY AND OBJECTS OF THE INVENTION

The basic task of the present invention is to provide a process that isdesigned such that it can be carried out with a device of simple design.

This task is accomplished by the transporting the first workpiece in asubstantially flat hanging position from a first transport means. Thesecond workpiece is also transported in a substantially flat positionfrom a second transport means. The first and second workpieces aretransported to a scanning and aligning station. At the scanning andaligning station one of the workpieces is removed from the respectivetransporting means and aligned with the other workpiece. After alignmenthas been completed the detached workpiece is reattached to therespective transport means. The two workpieces are then aligned andtransported in a substantially aligned manner for further processing.

A reduction of the overall alignment time is achieved if both workpiecesare detached from the respective transport means at the scanning andalignment station. During alignment each workpiece is moved in adirection substantially opposite the moving direction of the otherworkpiece. Both workpieces are then reattached to the respectivetransport means. Since each workpiece only has to move half thedistance, the alignment time is minimized. The alignment of the twoworkpieces can be done with respect to a reference line which may be apath of movement of a sewing machine moving along a straight linerelative to the aligned workpiece layers. If the angular alignment ofthe workpiece layers is also carried out by aligning movements takingplace in opposite directions, and the reference line is the bisector ofthe respective starting position of a defined edge of the workpiecelayers, it may be advantageous to adjust the path of movement of thesewing machine by correspondingly pivoting a guide rail carrying thesewing machine if the workpiece layers are connected by a sewing machinebeing moved along a straight line in relation to the workpiece layers.

Another task of the present invention is to provide a device forcarrying out the process, which is of simple design and does not requirestrong adjusting forces during the alignment of the workpiece layers.

The transport means have carriage means for connecting the workpieces tothe transport means or conveying means. The carriage means also have acarriage magnet. A clamp means holds the workpiece in a substantiallyflat hanging position and has a magnetizable support means in the formof a plate. This support plate attaches to the carriage means by theattraction of the carriage magnet. In the scanning and aligning stationthere is a scanning means for determining the relative position betweenthe first and second workpieces. The scanning and aligning station alsohas an alignment device. The alignment device has an aligning magnetmeans for magnetically transferring the clamp means from the carriagemeans to the aligning device. The aligning magnetic means has a magneticfield intensity that is switchable. This is preferably incorporated byan electromagnet. The carriage magnet can be a permanent magnet with thecoil surrounding it. In this way the magnetic fields of both magnets arecontrollable and the support plate of the clamp means can be attractedto either one of the magnets.

The aligning device has an adjusting means for moving the alignmentmagnet and the attached clamp means. Adjusting means working incooperation with the scanning means then aligns the two workpieces.

The present invention contains a hingedly movable device at the scanningand aligning station only, while the holding devices on the carriagesare essentially "rigid." During alignment, no adhesive and slidingfriction forces between the magnet and the magnetizable plate need beovercome, because the friction between the holding devices of theworkpiece layer(s) to be aligned and the associated transport means,which are designed as, e.g., carriages, is abolished during alignment.Together with the workpiece, the holding device is completely detachedfrom the transport means, aligned, and then again transferred to thetransport mechanism, where it will cling in frictional engagement due tothe force generated by the magnet and maintains the position which itassumes there.

The various features of novelty which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of this disclosure. For a better understanding of the invention,its operating advantages and specific objects attained by its uses,reference is made to the accompanying drawings and descriptive matter inwhich preferred embodiments of the invention are illustrated.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a synoptic view of a unit for feeding flaccid workpiece parts,e.g., fabric cuts, to a scanning and aligning station, as well as to asubsequent processing station, which is a sewing robot in this case,

FIG. 2 shows a sectional view of the scanning and aligning station, and

FIG. 3 shows a perspective detail of the essential elements of thealigning device in the scanning and aligning station.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings, and in particular to FIG. 1, a conveyingmeans 1 has a plurality of carriages 3 which serve as transportmechanisms and on which workpiece parts 4 hang. The carriages 3 aremoved by means of an endless circulating chain 2. Even though only threecarriages 3 are shown in this case, it is obvious that the chain isequipped with carriages 3 spaced at regular distances. The chain 2travels along an endless path around a wheel 6 driven by a motor 5 and adeflecting wheel 7 arranged at a spaced location from it. A scanning andaligning station 10 is located in the travel path of the chain 2. Asewing robot 8 is located downstream of the scanning and aligningstation when viewed in the direction of movement of the chain 2.

It should be noted that only one conveying means, whose transport pathextends through the scanning and aligning station 10, is shown inFIG. 1. However, to carry out the process according to the presentinvention, at least two of the conveying means are needed. Of the twoconveying means, the second also has a track section that extendsthrough the scanning and aligning station 10. For clarity's sake, thesecond conveying means is not shown in FIG. 1. However, it isrecognizable in FIG. 2.

FIG. 2 shows a front view of the scanning and aligning station 10. Twoguide rails 11 and 111, which are fastened to a common support frame 9,extend through this scanning and aligning station in parallel to oneanother. The guide rails 11 and 111 carry carriages 3 and 103, whichbelong to two separate conveying means, designated in their entirety by1 and 101, respectively. Each carriage 3 and 103 is provided withrunners 12 and 112, respectively, which guide the carriages 3 and 103,respectively, on the respective guide rail 11 and 111.

Only one of the carriages and the elements associated with it will bedescribed below. Since the other carriage and the elements associatedwith it are completely comparable, they are designated by referencenumerals increased by 100.

A holding plate 13 is fastened to the carriage 3, and the holding plate3 carries a permanent carriage magnet 14. The permanent carriage magnet14 is surrounded by a coil which is not recognizable in FIG. 2. By meansof the coil a magnetic field is generated which opposes the magneticfield of the permanent carriage magnet 14. This opposing magnetic fieldis generated in order to cancel the magnetic effect of the permanentcarriage magnet 14. Two bus bars 26, which are arranged stationarily ona bracket 25 cooperate with two sliding contacts 27 that are arranged onthe holding plate 13. The sliding contacts 27 are in electricalconnection with the coil, are used to supply the coil with power. Thepermanent carriage magnet 14 carries, due to the magnetic holding forceit generates, a magnetizable support 15 made of a plate of ferromagneticmaterial, to which a clamp 16 with a displaceable clamping body 17 isfastened. The clamp 16 with the displaceable clamping body 17 is able toclamp between it and the support plate 15 a flaccid workpiece layer 4,which hangs down from the support plate 15. The workpiece layer hangingdown now extends in a vertical plane at a closely spaced location fromand in parallel to the intermediate plate 18. The intermediate plate 18also extends vertically and is fastened to the support frame 9.Intermediate plate 18 is designed at least partially as an opticallyreflecting intermediate plate.

A pneumatic cylinder 19 is fastened at the side to the guide rail 11,and the pneumatic cylinder 19 has a thrust piece 20 that can be pushedforward toward the carriage 3 in order to fix it in the scanning andaligning station 10. The pneumatic cylinder 19 is connected to aprior-art control device, which is therefore not shown. Reflected lightphotocells 21, 22, and 23, which cooperate with the intermediate plate18, are also fastened to the guide rail 11 in an area that is adjacentto the area that is occupied by a workpiece layer 4 when it is locatedin the scanning and aligning station 10. The reflected light photocells21, 22, and 23 are thus able to detect the alignment of the workpiecelayer 4 and to send corresponding signals. The reflected lightphotocells 21, 22, and 23 are also connected to the above-mentionedcontrol device. A reflected light photocell 24, which serves torecognize the carriage 3, is arranged in the vicinity of the positionwhich carriage 3 assumes in the scanning and aligning station 10. Thisreflected light photocell 24 is also connected to the above-mentionedcontrol device.

An aligning device, designated in its entirety by 30, is arranged on thesupport frame 9 in the scanning and aligning station 10. The aligningdevice 30 comprises an aligning electromagnet 31 which generates amagnetic field that is able to carry the support plate 15 with theworkpiece layer 4 hanging on it. When carriage 3 is fixed by the thrustpiece 20 of the pneumatic cylinder 19 in the scanning and aligningstation 10, the aligning electromagnet 31 is located on the scanning andaligning station 10 at a site that is opposite the support plate 15. Thealigning electromagnet 31 will hereinafter be characterized essentiallyas a stationary electromagnet in order to clearly distinguish it fromthe permanent magnet that is carried by the carriage 3 which isconsequently a "movable" permanent magnet. The aligning electromagnet 31is fastened to a holder 32, which can be adjusted by an electric motorin a plurality of directions in a plane that extends in parallel to theplane defined by the workpiece layer 4.

As is shown in FIG. 3, the holder 32 is guided longitudinallydisplaceably in a first rail 33 that extends essentially vertically- Afirst electric motor 34 (cf. FIG. 2), is fastened to the rail 33 and bymeans of the first electric motor 34, the holder 32 can be adjusted inthe vertical direction via a threaded spindle 35. The first rail 33 isguided displaceably on a second rail 36 in an essentially horizontaldirection. The first rail 33 is displaced in relation to the second rail36 by means of an second electric motor 37, fastened to the second rail36, and a threaded spindle 38. The aligning electromagnet 31 isconsequently movable in two mutually substantially perpendiculardirections in the manner of a cross slide guide.

The second rail 36 is pivotably mounted on the support frame 9 by meansof a pivot pin, and the plane of pivoting is located in a planecontaining the two mutually substantially perpendicular directions inwhich the aligning electromagnet 31 is moved by the spindles 35 and 38.Pivoting movement of the second rail 36 can be brought about by means ofa third electric motor 40, which is hinged to the support frame 9 anddrives a third threaded spindle 41. The third threaded spindle passesthrough a threaded block 42 that is hinged to the second rail 36.

The electric motors 34, 37, and 40 are preferably stepping motors,because such motors can be set very accurately and are particularlysuitable, especially for digital energization. These electric motors arealso connected to the above-mentioned control device and are adjusted bythe control device depending on the signals sent by the reflected lightphotocells 21, 22, and 23.

The following movements of the electric magnet 31 can thus be broughtabout: a) up and down movement in the direction determined by the firstthreaded spindle 35 by means of the first electric motor 34; b) amovement essentially in parallel to the path of movement of the carriage3 in the direction determined by the second threaded spindle 38 by meansof the second electric motor 37; and c) a pivoting movement around thepivot pin 39 by means of the third electric motor 40 and the thirdthreaded spindle 41 driven by it.

The mode of operation of the device shown is as follows:

In the normal state of transport of the workpiece layers 4, as shown inFIG. 1, the coils on the permanent magnets 14, which are carried by thecarriages 3, are not energized, so that the permanent magnets 14 holdthe support plates 15 with the workpiece layers 4 hanging on them. Thealigning electromagnet 31 is not energized. When a carriage 3 hasarrived in the scanning and aligning station 10, the chain 2 of theconveying means is temporarily stopped, so that all the carriages 3carried by it will come to a stop. The carriage 3 located in thescanning and aligning station 10 is fixed in the stopped position in thescanning and aligning station 10. The magnetic field of the permanentcarriage magnet 14 is then neutralized by energizing the coil belongingto the permanent carriage magnet 14. The aligning electromagnet 31 isenergized at the same time, so that aligning electromagnet 31 will nowhold the support plate 15 with the workpiece layer 4 hanging on it,while the permanent carriage magnet 14 is released from the supportplate 15.

The workpiece layer 104, which is to be processed together with theworkpiece layer 4, is simultaneously delivered by the other conveyingmeans, which is designated in its entirety by the reference numeral 101in FIG. 2. The workpiece layer 104 is delivered into the scanning andaligning station 10, and is stopped in the scanning and aligning station10. The reflected light photocells 21, 22, 23, and 121, 122, and 123 nowdetect the positions of the workpiece layers 4 and 104 and sendcorresponding measurement signals to the control device (not shown). Thecontrol device generates control commands necessary for the alignment ofthe two workpiece layers 4 and 104 according to predeterminedspecifications. These control commands are sent as signals to theelectric motors 34, 37, and 40 of the aligning device 30. The angularposition of the front edge of the workpiece layers 4, 104, which extendin the downward direction, is first determined by the reflected lightphotocells 22, 23 and 122, 123. Angular alignment of the workpiecelayers 4 and 104 is performed by energizing the electric motor 40 and/or140 in the case of deviations from the desired aligned position. Therelative vertical position of the two workpiece layers 4 and 104, on theone hand, and, on the other hand, the relative horizontal position ofthe two workpiece layers 4 and 104 are then determined by means of thereflected light photocells 21, 23 and 121, 123. Mutual alignment of theworkpiece layers 4 and 104 is performed by energizing the correspondingelectric motors 34; 37; 134; 137 in the case of a difference. Thevertical and horizontal alignments are performed by simultaneouslyenergizing the corresponding electric motors 34, 134 and 37, 137,respectively, of the two aligning devices 30, 130 in oppositedirections, as a result of which the time needed for alignment isreduced to a minimum.

The alignment of the workpiece layers 4 and 104 may be performed withoutappreciable frictional forces between the respective support plate 15;115 and the corresponding permanent magnets 14; 114. This occurs becauseThe magnetic field of the permanent magnets 14:114 is canceled by thatof the surrounding current-carrying coils. Once the necessary alignmenthas been accomplished, energization of the coil is abolished, so thatthe permanent magnets 14; 114 will again develop its attracting force,and the energization of the opposing electromagnets 31, 131 is turnedoff, so that the support plates 15; 115 will again be transferred to thepermanent magnets 14; 114. As was mentioned above, the holding force ofthe permanent magnets 14; 114 selected to be sufficient so that theposition of the support plate 15; 115 on the permanent magnets 14:114cannot change. The two conveying means 1, 101 are then again put intooperation, so that the two workpiece layers 4 and 104 will leave thescanning and aligning station 10 together and in a mutually alignedposition.

It should be pointed out that it is sufficient for alignment purposes tomove only one of the workpiece layers 4 or 104 with the correspondingaligning device 30 or 130 shown in FIG. 3 to bring about mutualalignment. It is not necessary for the other conveying means also to bedesigned in the above-described manner. It is consequently possible, forexample, to abandon the permanent magnets 114 on the carriage 103 of theother conveying device 101. The support plates 115 may be permanently,i.e., nondetachably, connected to the carriages 103 there, and thealigning device 130 associated with the conveying means 101 may beabsent in the scanning and aligning station 10. However, the reflectedlight photocells 121, 122, and 123 for scanning the fabric layer 104must always be present. The embodiment of the device shown in FIG. 2, inwhich the two conveying means 1, 101 have the same design and aligningdevice 30 and 130 associated with the two conveying means 1, 101,respectively, in the scanning and aligning station 10, offers theabove-described advantage of more rapid operation and an increased inthe possibilities for correction.

I claim:
 1. A process for aligning first and second flaccid workpiecelayers, the process comprising the steps of:transporting the firstworkpiece in a substantially flat hanging position from a firsttransport means; transporting the second workpiece in a substantiallyflat hanging position from a second transport means; detaching one ofsaid first and second workpieces from said respective transportingmeans; aligning said detached workpiece with the other workpiece in oneof substantially horizontal and vertical directions; reattaching saiddetached workpiece to said respective transport means; and transportingsaid aligned first and second workpieces together in a substantiallyaligned manner for further processing.
 2. Process in accordance withclaim 1, further comprising:detaching the other of said first and secondworkpieces from said respective transporting means before saidalignment; and said workpieces are aligned with one of an edge andreference points of an edge, being substantially in parallel with apredetermined reference line, said alignment being by moving saiddetached first and second workpieces in substantially oppositedirections, said substantially opposite directions being one ofsubstantially parallel and perpendicular to said predetermined referenceline.
 3. Process in accordance with claim 1, wherein:said reference lineforms a bisector of a respective starting position of said alignmentedge of the first and second workpieces.
 4. Process in accordance withone of the preceding claims 1 through 3, further comprising:stoppingsaid transporting of the first and second workpieces before saiddetaching; and restarting said transporting after said aligning of theworkpieces.
 5. A device for aligning first and second flaccid workpiecelayers, the device comprising:a first conveying means for transportingthe first workpiece along a first path, said first conveying meanshaving carriage means for connecting the first workpiece to said firstconveying means, said carriage means having a carriage magnet; firstclamp means for holding the first workpiece in a substantially flathanging portion, said clamp means having a magnetizable support meansfor attaching to said carriage magnet; a second conveying means fortransporting the second workpiece along a second path, said second pathhaving a portion adjacent said first path, said second conveying meanshaving carriage means for connecting the second workpiece to said secondconveying means, said carriage means having a carriage magnet; secondclamp means for holding the second workpiece in a substantially flathanging position, said clamp means having a magnetizable support meansfor attaching to said carriage magnet; a scanning and aligning stationpositioned in said first and second path at said portion where saidfirst path is adjacent said second path, said scanning and aligningstation having scanning means for determining the relative position ofthe first and second workpieces, said scanning and aligning station alsohaving an alignment device movably connected to said scanning andalignment station, said aligning device having an aligning magnet meansfor magneticly transferring one of said first and second clamp meansfrom said carriage means to said aligning device, said aligning magnetattaching to said magnetizable support, said aligning magnetic meanshaving a magnetic field intensity alternatingly switchable with a fieldintensity of said carriage magnet to transfer said one of said first andsecond clamp means to said aligning device, said aligning device havingadjusting means for adjusting a position of one of the first and secondworkpieces relative to the other of the first and second workpieces. 6.Device in accordance with claim 5, wherein that the:said scanning andalignment station has another aligning device similar to said aligningdevice, said aligning device transferring said first clamp means fromsaid first conveying means and said another aligning device transferringsaid second clamp means from said second conveying means; and saidanother aligning device having an adjusting means for adjusting a secondposition of the second workpiece substantially opposite to adjustingdirections of said adjusting means of said aligning device.
 7. Device inaccordance with claim 5 or 6, wherein:said carriage magnet means has apermanent magnet and a coil means for generating a magnetic fieldsubstantially opposing a magnetic field of said permanent magnet. 8.Device in accordance with claim 7, wherein:said carriage means haselectrical contact means for receiving power for said coil means; andsaid scanning and aligning station has electrical contact means fortransferring said power to said electrical contact means of carriagemeans.
 9. Device in accordance with claim 8, wherein:said contact meansof said carriage means and said scanning and aligning station aresliding contacts.
 10. Device in accordance with claim 5, wherein:saidadjusting means displaceably guides said aligning magnet means in afirst, substantially vertically extending rail.
 11. Device in accordancewith claim 10, wherein:said first rail is displaceably guided on asecond rail extending transversely to said first rail.
 12. Device inaccordance with claim 11, wherein:said second rail is pivotably mountedon a stationary support structure.
 13. Device in accordance with claim5, wherein:said aligning device is driven by an electric motor. 14.Device in accordance with claim 5, wherein:said adjusting means haselectric motors designed as stepping motors.